Petra Kvitova of the Czech Republic returns a shot to Li Na of China during the China Open tennis tournament at National Tennis Stadium in Beijing, China Friday, Oct. 4, 2013. (AP Photo/Andy Wong (The Associated Press)

Serena Williams of U.S. holds her winning trophy and waves to her fans after the final of the China Open tennis tournament at the National Tennis Stadium in Beijing, China, Sunday, Oct. 6, 2013. Williams defeated Jelena Jankovic of Serbia 6-2, 6-2. (AP Photo/Andy Wong) (The Associated Press)

Jelena Jankovic of Serbia reacts after defeating Petra Kvitova of the Czech Republic during the semifinal of the China Open tennis tournament at the National Tennis Stadium in Beijing, China Saturday, Oct. 5, 2013. (AP Photo/Andy Wong) (The Associated Press)

LONDON – Maria Sharapova has withdrawn from the season-ending WTA Championships because of an injured right shoulder.

The WTA says the third-ranked Russian will miss the Oct. 22-27 tournament in Istanbul because of the injury, which has sidelined her for most of the second half of the year.

Sharapova thanked Istanbul for being a "tremendous host" and said she hopes to play in Turkey in the future.

The WTA says Petra Kvitova of the Czech Republic, Sara Errani of Italy and Jelena Jankovic of Serbia have qualified for the championships. They join a field that already includes Serena Williams, Victoria Azarenka, Agnieszka Radwanska and Li Na.

The tournament features the top eight singles players and top four doubles teams.